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| Titel |
A generation mechanism for chorus emission |
| VerfasserIn |
V. Y. Trakhtengerts |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 17, no. 1 ; Nr. 17, no. 1, S.95-100 |
| Datensatznummer |
250013647
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| Publikation (Nr.) |
 copernicus.org/angeo-17-95-1999.pdf |
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| Zusammenfassung |
A chorus generation mechanism is discussed,
which is based on interrelation of ELF/VLF noise-like and discrete emissions
under the cyclotron wave-particle interactions. A natural ELF/VLF noise
radiation is excited by the cyclotron instability mechanism in ducts with
enhanced cold plasma density or at the plasmapause. This process is accompanied
by a step-like deformation of the energetic electron distribution function in
the velocity space, which is situated at the boundary between resonant and
nonresonant particles. The step leads to the strong phase correlation of
interacting particles and waves and to a new backward wave oscillator (BWO)
regime of wave generation, when an absolute cyclotron instability arises at the
central cross section of the geomagnetic trap, in the form of a succession of
discrete signals with growing frequency inside each element. The dynamical
spectrum of a separate element is formed similar to triggered ELF/VLF emission,
when the strong wavelet starts from the equatorial plane. The comparison is
given of the model developed using some satellite and ground-based data. In
particular, the appearance of separate groups of chorus signals with a duration
2-10 s can be connected with the preliminary stage of the step formation. BWO
regime gives a succession period smaller than the bounce period of energetic
electrons between the magnetic mirrors and can explain the observed intervals
between chorus elements.
Key words. Magnetospheric physics (Energetic particles
· trapped). Space plasma physics (wave-particle interactions; waves and
instabilities) |
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